Grinding



Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE 2,177,316 GRINDING Jersey No Drawing. Application April 11, 1936, Serial No. 73,938

5 Claims.

This invention relates to oil mixtures to facilitate the grinding or polishing of metals and more particularly to the grinding or polishing of sheet-like metals of the stainless type, although not necessarily limited thereto.

Such grinding or polishing is usually accomplished by reciprocating the metallic Work-piece, such as a sheet, beneath rolls or endless belts coated with a suitable abrasive. The abradant grains of the belt or roll contacting the workpiece under pressure usually breaks off into smaller granular particles, which unduly scores or scratches the surface of the metal Work-piece and produces a dust detrimental to the health of workmen nearby. As the belt continues to wear its surface becomes flatter and duller, and as a result generates more frictional heat which not only weakens the belt but also burns the surface of the metal being ground or polished.

These disadvantages are overcome by our invention, it being our prime object to materially increase the abradant life of the grinding or polishing medium.

Another object is to provide an abrading surface which at all times is clean and sharp, thus presenting maximum abrading action throughout its life.

Still another object is to provide increased rapidity of grinding or polishing, with heavier and coarser abradants, by minimizing frictional heat and without warping or twisting the workpiece.

Other objects include minimizing unhealthful abradant dust and freedom of excessive scratching of work-pieces. These and other objects will become apparent to those skilled in the art when considered in the light of the following description of our grinding mixture.

It will be admitted that various oils have been utilized in conjunction with abradant grinding or polishing processes but they are satisfactory only when rough or heavy grinding and tend to clog the grinding belts or rolls. The major portion of grinding or polishing of metallic surfaces, such as stainless steel sheets and the like, have therefore been on dry belts or rolls.

We have discovered that by using a mixture of palm oil and kerosene that the various objects outlined above are apparent. Palm oil is utilized as it presents an oil which will hold its body and viscosity at relatively high temperatures as usually developed in friction grinding. The use of kerosene or other volatile oils alone cannot be tolerated due to their low flash point but when used to dilute or cut back a high flash point palm oil such a mixture has many advantages. For example, in the rough grinding of sheet metal the loose abradant or oil alone tends to accumulate between the abrasive grains, thus lowering the cutting eiiect. A mixture of palm oil and 25% kerosene contacting rough grinding abrasives will flush out such dust or oil lying between the large abradant grains and present sharp cutting grains which increases cutting action and the life of the abrading belt or roll, takes away in solution the abrasive dust and minimizes friction. The removal of the dust practically eliminates excess scratching and scoring of the surface of the work-piece by such loose particles.

With minimized heat the use of a coarser grit or grain is permissible with well defined and obvious results. If the abrading grains are coarse enough one may start with straight palm oil, but as the belt clogs with dust and oil the above mixture is utilized for the remaining life of the belt.

The intermediate grinding or polishing of metallic work-pieces presents the same problems as in rough grinding but are accentuated by the use of a finer grit or grain which may necessitate starting a new belt in contact with an oil mixture comprising approximately half the palm oil and half kerosene which continually flushes out between the more closely spaced grains. In both rough and intermediate grinding the normal abrading life of such belts is more than doubled by the use of our mixture above described.

It is entirely and often permissible to start either or both rough and intermediate grinding operations on straight palm oil regardless of the size of the abrading grains, but in any event the palm-oil-kerosene mixture is added as soon as the effective abrading of the belt is noticeably lessened, the flushing action between the abradant grains being accelerated by additional kerosene as the grains are more closely spaced. In either case the final mixture, at the time the abrading belt or roll is replaced, approximates 50% kerosene and 50% palm oil.

The full advantages of our invention will be apparent to those skilled in the art. The proportion of kerosene and palm oil are not limited to those specifically mentioned herein, as such factors as speed and pressure of cutting, type of abradant and the manner of its use (roll or belt) as well as the nature of the work-piece being ground or polished all affect the proportion of the ingredients.

Other changes may be made within the scope of the invention as defined in the claims, wherein we claim:

1. A method of grinding or polishing sheet metal by means of a roll or belt coated with abrasive grains, including flushing said grains with palm oil during the grinding or polishing so as to remove loosened grains from between those remaining on said roll or belt and to prevent the formation of dust resulting from said loosened grains.

2. A method of grinding or polishing sheet metal by means of a roll or belt coated with abrasive grains, including flushing said grains with palm oil during the grinding or polishing so as to remove loosened grains from between those remaining on said roll or belt and to prevent the formation of dust resulting from said loosened grains, said palm oil being thinned with kerosene as required to produce a mixture suited to the sizes of said grains.

3. A method of grinding or polishing sheet metal by means of a roll or belt coated with abrasive grains, including flushing said grains with a mixture of palm oil and not more than per cent kerosene during the grinding or polishing so as to remove loosenedgrains from between those remaining on said roll or belt and to pretheir interstices free from accumulations tending to retard their normal abrasive effect.

5. A method of grinding or polishing sheet metal by means of a roll or belt coated with abrasive grains, including flushing said grains with palm oil during the grinding or polishing so as to remove'loosened grains from between those remaining on said roll or belt and to prevent the formation of dust resulting from said loosened grains, and as said grains became smaller by use, the flushing of said smaller grains with a mixture of palm oil and not more than 50 per cent kerosene during the grinding or polishing to accomplish similar results as obtained by the useof palm oil alone when said grains were of larger size.

HENRY H. GILES.

CARL M. NYSTROM. 

